Paul Graham originally introduced me to the idea that programming in a niche language was a good idea. He makes great arguments for organizations adopting more powerful languages and hiring smaller teams of highly effective programmers that can harness the power of niche languages. Paul Graham made me feel good about working exclusively on Ruby projects.

Later I read (the fantastic) My Job Went to India by Chad Fowler. Chad also talks about how being proficient in a niche language can make you a more valuable asset. Again, I felt good about focusing so heavily on Ruby.